A need exists in the medical field for a positioning arm for holding and stabilizing devices used in medical procedures. For example, in the field of breast biopsy, a biopsy power driver and probe, such as that disclosed in U.S. Pat. No. 5,526,822, commonly assigned with the present application, is known for percutaneously obtaining tissue samples for analysis. However, to successfully perform the procedure, it is necessary to stabilize and restrain the power driver and probe to ensure accurate placement of the probe into the breast from any desired entry point. Furthermore, once the probe has been properly positioned within the patient at the lesion site, its position must be closely maintained for an extended period of time during the tissue sampling process. Presently, either the physician or an assistant to the physician performing the procedure often undertakes this function, but fatigue often results, leading to unintended movement of the probe. As a result, numerous attempts to accurately position the probe are often necessary. In a worst case, if the unintended movements due to human error are not detected by the practitioner, the location biopsied may not be the one desired.
The present invention solves the aforementioned problems by providing a device having great positional flexibility, which stabilizes and positions the biopsy power driver and probe as desired to ensure the ability to accurately place the probe into the breast and maintain position relative to the target tissue from any desired entry point.
More particularly, an apparatus is provided for securing and positioning medical instruments, which comprises a main arm having a generally vertical portion and a generally horizontal portion. A clamping assembly permits attachment of the apparatus to a stationary object, which is preferably an examination table. The clamping assembly comprises a locking clamp having a gripping mode and a releasing mode for alternately gripping and releasing the main arm, and a lever assembly for actuating the locking clamp between the gripping mode and the releasing mode. A horizontal clamp is attached to the generally horizontal portion of the main arm. An articulating arm assembly having a first arm portion, or upper arm, and a second arm portion, or forearm, is provided, wherein the upper arm and forearm are attached together by an elbow joint, so that they may be rotated relative to one another about a common axis. A proximal end of the upper arm is attached to the horizontal clamp by means of a shoulder joint, which preferably provides a rotational capability through a 360 degree range. Yet another joint, hereinafter referred to as a xe2x80x9cwristxe2x80x9d, is disposed at a distal end of the forearm, to which is attached a mounting bracket for securing a medical instrument, such as a biopsy power driver and probe, thereto. Both the elbow and wrist joints provide relative angular motion for the articulating arm portions. The articulating arm assembly is further adapted to swing out of the way while the patient is being positioned for a medical procedure.
One advantageous feature of the present invention is that the generally vertical main arm portion is adjustable in height, in order to compensate for anatomical variations in individual patients, and is adjustable radially in order to provide access to either side of the patient""s body.
Another advantageous feature of the present invention is that the locking clamp is spring biased to its gripping position, so that it is only maintained in its releasing position by actuating (pushing or pulling) and holding the lever assembly, thereby ensuring that the main arm is held in a fixed position at all times other than when it is desired to adjust the relative position of the apparatus with respect to the patient. The lever assembly is particularly designed to ensure that it may be easily reached and actuated by a user standing anywhere along the head end or along either side of the examination table. This design preferably includes a laterally extending looped member which extends beneath the examination table such that portions of the looped member are proximate to each of the head end and two sides thereof. However, other configurations may be utilized as well, as long as they are of a symmetrical construction in order to provide ready access from any of the head end or either side of the table.
Still another advantageous feature of the invention is that the elbow joint attaching the upper arm and forearm of the articulating arm assembly comprises a spring loaded counterbalance mechanism which functions to support the weight of a medical instrument attached to the mounting bracket of the apparatus, thereby giving the instrument a weightless feel during the positioning process, which prevents fatigue on the part of a user and therefore permits more delicate and precise movements of the instrument.
Yet another advantageous feature of the invention is the inclusion of a micro-advance mechanism disposed distally of the aforementioned wrist joint, which, after fully restraining all clamps, permits fine adjustment of the linear position of a medical instrument attached to the mounting bracket. Significantly, the micro-advance mechanism is self-locking; i.e. it has sufficient friction such that it only moves upon actuation of an adjustment knob.
In another aspect of the invention, an apparatus for securing and guiding medical instruments is provided which comprises a main arm to which a medical instrument may be secured and a clamping assembly for attaching the main arm to an examination table. The examination table has a head end, a foot end, and two sides, and the clamping assembly comprises a locking clamp having a gripping mode and a releasing mode for alternately gripping and releasing the main arm, as well as a lever assembly for actuating the locking clamp between the gripping mode and the releasing mode. Advantageously, the lever assembly comprises a vertical member joined to the locking clamp and extending downwardly therefrom, and a laterally extending symmetrical member, which is preferably of a looped configuration, joined to the downwardly extending member. The looped member extends beneath the examination table such that portions of the looped member are proximate to each of the head end and the two side ends. It is conveniently located sufficiently inwardly from the table edges to prevent inadvertent actuation or release. With such a construction, a user may reach a portion of the looped member while standing at any of the head end or either side of the examination table and actuation of any portion of the looped member causes the vertical member to either swivel or move vertically, thereby actuating the locking clamp to the releasing mode.
In still another aspect of the invention, an apparatus for securing and guiding medical instruments is provided which comprises a main arm and an articulating arm assembly having a first end and a second end. The first end is attached to the main arm and the second end is attached to a holder to which a medical instrument may be mounted. Advantageously, a micro-advance mechanism is disposed at the second end for permitting fine adjustment of the linear position of a medical instrument attached to the holder.
The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawing.